What keeps nuclear fusion from going out of control in a main sequence star?

a. Gravitational force toward the outer part of the star keeps the core under control.



b. Fusion absorbs heat, so the reaction limits itself.



c. If the reaction were to increase, the core would expand and slow the reaction.



d. Nearby stars exert enough gravitational force to control the reaction.What keeps nuclear fusion from going out of control in a main sequence star?c. is the best answer.

As the reaction speeds up the temperature rises and the star expands reducing core density.What keeps nuclear fusion from going out of control in a main sequence star?None of these answers is completely correct. Gravity cannot work outwards, so a. is incorrect. Gravity works inward pressure works in all directions, increasing with depth. Gravity and pressure balance each other in a main sequence star. The pressure and temperature in the core of a proto- main sequence star is high enough to initiate fusion and then maintain fusion, when the star moves onto the main sequence after the T-Tauri phase. If you have no idea what a T-Tauri phase is, you can either Google it or read about it in Wikipedia.



c. will not start to happen until the star starts running out of hydrogen in core.



http://en.wikipedia.org/wiki/T-Tauri_sta鈥?/a>



http://zebu.uoregon.edu/~js/ast122/lectu鈥?/a>



http://en.wikipedia.org/wiki/Stellar_cla鈥?/a>What keeps nuclear fusion from going out of control in a main sequence star?A. The pressure from the envelope keeps it from going out of control. Then at the end of main sequence when the fuel is all used up, it collapses then begins shell hydrogen burning as a red giant.What keeps nuclear fusion from going out of control in a main sequence star?
C.



If the reaction were to increase, the core (and entire star) would swell and cool, slowing the reaction.